Tests and diagnosisBy Mayo Clinic staff
Doctors usually diagnose seborrheic dermatitis by taking a thorough medical history, listening carefully to what you say about your symptoms and examining the skin areas that are troubling you.
Steps to diagnosis include:
- Medical history. Your doctor will ask about your symptoms, all the prescription and over-the-counter medications you're taking, and your other health conditions.
- Physical examination. Your doctor will examine your scalp and areas of your face or body where you have symptoms.
- Skin biopsy. Your doctor may scrape cells off your skin and examine them under a microscope or take a skin sample (biopsy) for detailed analysis in a laboratory. These tests may help confirm your diagnosis by ruling out other skin conditions.
Conditions with some symptoms similar to seborrheic dermatitis include:
- Psoriasis. This disorder also causes red skin covered with flakes and scales. The flakes tend to look more silvery and usually extend beyond the hairline of your scalp. Patches can range from a few spots of scaling to major eruptions that cover large areas of the body. The parts of your body affected may differ from the typical pattern of seborrheic dermatitis. Like seborrheic dermatitis, psoriasis can cause dandruff.
- Atopic dermatitis (eczema). This skin reaction causes itchy, inflamed skin. It often occurs in the folds of the elbows, on the backs of the knees or on the front of the neck. It tends to flare periodically and then subside for a time, even up to several years.
- Ringworm of the scalp (tinea capitis). This fungal infection is most common in toddlers and school-age children. It causes red, itchy, bald-looking patches on the scalp.
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